Method whenRenderStarted

src/friendly-iframe-embed.js:438–440

* Returns a promise that will resolve when the embed document is ready. * Notice that this signal coincides with the embed's `render-start`. * @return {!Promise}

()

   * @return {!Promise}
   */
  whenRenderStarted() {
    return this.signals_.whenSignal(CommonSignals_Enum.RENDER_START);
  }

  /**
   * Returns a promise that will resolve when the child window's `onload` event